A Comprehensive epidemiological and molecular study of gastrointestinal helminths of Companion Animals in Northeastern Bangladesh: A neglected zoonotic threat

ABSTRACT Background Gastrointestinal helminths of companion animals are neglected sources of zoonotic infection in low and middle-income countries. In Bangladesh, close humananimal contact and large free-roaming dog and cat populations may facilitate parasite transmission, yet region-specific data remain limited. This study assessed the prevalence, species diversity, and zoonotic potential of gastrointestinal helminths in companion animals in northeastern Bangladesh. Methods A cross-sectional study was conducted between January and December 2025 across urban and rural areas of the Sylhet Division. Fecal samples from 900 animals (600 dogs and 300 cats; owned and stray) were examined using standard coproscopic techniques. Molecular confirmation of selected positive samples was performed using PCR targeting ITS-2, 18S rRNA, and mitochondrial cox1 genes, followed by sequencing. Risk factors associated with infection were evaluated using multivariable logistic regression. Results Overall, 45.9% (95% CI: 42.6–49.2) of animals were infected with at least one gastrointestinal helminth, with mixed infections detected in 18.4%. Prevalence was similar in dogs (45.7%) and cats (46.3%) but significantly higher in stray animals (65.7%) than in owned animals (36.6%). Predominant zoonotic helminths included Ancylostoma spp ., Toxocara canis, Toxocara cati, Dipylidium caninum , and Taenia/ Echinococcus spp . Molecular analysis confirmed 93% of morphologically identified infections and revealed high genetic similarity to zoonotic reference strains. Stray status, lack of deworming, young age, and outdoor roaming were significant risk factors for infection (p < 0.05). Conclusions Companion dogs and cats in northeastern Bangladesh harbor a high burden of zoonotic gastrointestinal helminths and represent important reservoirs for human exposure. Strengthening One Health–based surveillance, routine deworming, and stray animal management is essential to reduce zoonotic transmission.